my all-sky balcony cam consists of a cctv camera with a cheap, non-wide-angle lens directed (downwards) at a convex mirror - a silvered christmas tree ornament works.I call it my poor-man's fisheye lens; Set up more than one in varying directions to get better coverage/ better resolution. Admittedly; a bit of a deviation from your design but I thought it as not inappropriate to share. And thank you for sharing!